Knee brace with adjustable rigid posterior strut

ABSTRACT

A knee brace has an adjustable rigid posterior strut with an arcuate member which extends through the popliteal space behind the knee joint and is made of two halves which can be extended or retracted axially or rotated with respect to one another. Terminal portions of the strut, to which supports secured to the leg and thigh are hinged, are adjustably secured by ball and socket connections to mounting members which in turn are adjustably attached to the arcuate member by stems which telescope into and rotate within bores in the ends of the two halves of the arcuate member. With these adjustments the components of the posterior strut can be locked in a myriad of configurations to accommodate for various sizes and deformities of protected joints.

BACKGROUND OF INVENTION

1. Field of Invention

This invention relates to a knee brace with a posterior strut andgenerally triangular stiff cuff members which transmit forces around theknee joint, and more particularly to such a knee brace in which therigid posterior strut is adjustable in several degrees of freedom toaccommodate for a wide range of abnormalities in, and sizes of, theprotected joint.

2. Background Information

Our copending application Ser. No. 07/662,879 filed on Mar. 1, 1991 nowU.S. Pat. No. 5,133,341 and entitled "Knee Brace with Posterior Strut"discloses a unique knee brace having a rigid posterior strut with anarcuate section extending through the popliteal space behind the kneejoint and terminal portions positioned on either side of, but spacedfrom, the joint. A superior elongated support member is pivotallyconnected to one terminal portion of the strut and extends upward alongone side, preferably the medial side, of the thigh, and is secured tothe fleshy part of the thigh by cushioned straps. An inferior elongatedsupport member is pivotally connected to the other terminal portion ofthe strut and extends downward along the opposite side, preferably thelateral side, of the leg and is secured to the fleshy part of the leg byadditional cushioned straps.

The posterior strut of this brace performs several functions. First, itis the basic element to which the other components of the brace areattached. Second, it transmits forces applied to the lateral side of theknee around the joint to the medial side and into the fleshy part of thethigh through the hinged support. Similarly, medially applied forces aretransmitted around the knee joint by the posterior strut to the lateralside where they are dissipated in the fleshy part of the leg.

A third and very important function of the posterior strut is therepositioning of the hinge points for the support members on theterminal portions of the strut to accommodate for femoral rollbackduring flexion of the joint. This repositioning is effected by rotationof the arcuate portion of the strut which is clamped between the fleshyportions of the backs of the thigh and the calf. This constructioneliminates the need for the very complex compound hinge mechanisms foundin many knee braces.

The knee brace of our copending application also preferably includes apair of stiff, bowed anterior cuffs. These cuffs are generallytriangular in shape with one edge secured to one of the elongatedsupports and the opposite vertex pivotally connected to the oppositeterminal portion of the strut. These stiff cuffs, together with theposterior strut, transmit torsion forces around the knee joint withoutinterfering with normal flexion of the joint. As an elongated supportneed only be attached to one side of the thigh and the other side of theleg, the unique Z configuration of our knee brace makes it easier to fitthe brace to the wearer, while providing superior protection. In analternative, functional (special application) form of the brace,elongated support members hinged to both the terminal portions of theposterior strut extend upward and downward and are attached to thelateral and medial sides of both the thigh and the leg. Pairs ofcriss-crossing, stiff, anterior cuffs are secured to each of theelongated support members and are pivotally connected to the oppositeterminal portion of the posterior strut.

While the knee brace of our copending application provides very goodsupport for an injured, diseased or malformed knee joint, there is aneed for a knee brace with a posterior strut which can be readily andeasily adjusted to accommodate for individual knee characteristics andprovide the surgeon/physiotherapist with a means for adjusting forabnormal knees for either improved brace fit, optimizing bracefunction/action for individual patients, or compensating for orcontrolling specific motions or actions. Adjustments may also berequired or desirable during the course of treatment to accommodate forreduction in swelling, changes caused by treatment, or growth as in achild. It would also be desirable to have a single, or only a few basicsizes of the brace, which could be readily adapted to the circumstances,as opposed to the custom modeling and fabrication or the stocking ofnumerous sizes as required by many other braces.

SUMMARY OF THE INVENTION

These and other needs are satisfied by the invention which is directedto a posterior strut, and a knee brace incorporating the posteriorstrut, which is adjustable in many degrees of freedom to accommodate forindividual joint characteristics and abnormalities, and changes thereof,and to reduce the number of sizes of the brace which must be stocked.

More particularly, the terminal members of the strut are connected tothe arcuate center member by mounting means adjustably fixing theterminal members to the ends of the arcuate member in selectedpositions. Such adjustments include axial and rotational positioning ofthe terminal members relative to the longitudinal axis of the arcuatemember. They may further include rotational adjustment of the terminalmembers about lateral and vertical axis transverse to the longitudinalaxis of the arcuate member. Preferably, the mounting means includesmounting members having elongated members which telescope within boresin the ends of the arcuate member and which are secured in the selectedaxial and rotational positions by clamps which may be formed byconfronting flanges on each side of slits along the bores in the ends ofthe arcuate member and screws which draw the flanges together.

The mounting means also includes attachment means fixing the terminalmembers to the mounting members in selectable positions. Preferably, theattachment means is a ball and socket connection. With this arrangement,the terminal members may be fixed in any angular position desiredrelative to the arcuate member and the anterior/posterior size of thestrut can be adjusted.

Also preferably, the arcuate member comprises two halves joined by anelongated piece which telescopes into the two halves. The two halves maybe extended axially along the elongated piece to adjust thelateral/medial dimension of the strut, and rotated about the elongatedpiece to adjust their relative angular positions in the sagittal(anterior-posterior) plane. The two halves of the arcuate member areclamped to the stem in the selected axial and angular positions byclamps similar to those which secure the terminal member mounts to theends of the arcuate member. Preferably, the elongated members of themounts and the elongated piece joining the two halves of the arcuatemember, as well as the bores in the arcuate member are fluted to moresecurely fix the parts in the selected positions.

The knee brace incorporating the strut has generally triangular, stiffcuffs secured along one edge to one of the support members hinged to theterminal members and extending either upward along the thigh or downwardalong the leg. The opposite vertex is pivotably connected to theterminal member on the opposite side. These cuffs are anterior to thethigh and leg and are bowed so that they can accommodate for smalladjustments of the terminal members. For larger adjustments, the cuffsare attached to the elongated member by a pivot member and fasteningmeans spaced from the pivot member which accommodates for rotation ofthe cuff about the pivot member to a selected angular position andfixedly secures the cuff to the elongated support member at the selectedangular position. Preferably, the fastening means are slots in the cuffsand fasteners extending through the slots and clamping the cuffs in theselected positions.

BRIEF DESCRIPTION OF THE DRAWINGS

A full understanding of the invention can be gained from the followingdescription of the preferred embodiments when read in conjunction withthe accompanying drawings in which:

FIG. 1 is a front elevation view of a knee brace in accordance with theinvention shown in use protecting a right knee joint shown in extension.

FIG. 2 is a side elevation view of the knee brace of FIG. 1.

FIG. 3 is a side elevation view similar to FIG. 2 but showing the kneejoint flexed.

FIG. 4 is an isometric view in enlarged scale of a posterior strut whichforms a part of the knee brace of FIGS. 1 and 2.

FIG. 5 is a fragmentary view, partially in section, of one end of theposterior strut shown in FIG. 4.

FIG. 6 is a fragmentary side view of a portion of the knee brace of theinvention illustrating a mechanism for adjustment of the cuffs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a knee brace in accordance with the invention in usein supporting and stabilizing a knee joint 1 of a human right lowerextremity 3. The knee joint 1 is formed by the enlarged ends of thefemur 5, which is the bone of the thigh 7, and the upper end of thetibia 9 which together with the fibula 11 form the bones of the leg 13.The patella (knee cap) 14 articulates with the distal end of the femur5.

The joint 1 is held together by an arrangement of ligaments includingthe anterior cruciate ligament 15, the posterior cruciate ligament 17,the lateral collateral ligament 19 and the medial collateral ligament21. Shear forces and torsional forces applied to the knee joint canresult in stretching, and even tearing of these ligaments. A commoninjury occurs when a lateral blow is applied to the outside of the thighwith the foot planted. This causes the knee joint to buckle inwardresulting in tearing of the medial collateral ligament 21, andoccasionally the anterior cruciate ligament 15 as well.

The knee brace of the present invention is an improvement upon the kneebrace described in our copending U.S. application Ser. No. 07/662,879filed on Mar. 1, 1991 which is hereby incorporated by reference. Theimproved knee brace of the present invention provides several degrees offreedom in adjustment of the knee brace of the copending application.

The improved knee brace 23 shown in FIGS. 1 and 2 includes an adjustablerigid posterior strut 25. The strut 25 comprises an arcuate member 27which extends behind the knee joint 1 through the popliteal area 29 (seeFIG. 2). Terminal members 31 and 33 are secured to the arcuate member 27by mounting members 35 and 37 respectively. The terminal members 31 and33 are adjacent, but spaced from the lateral and medial sides,respectively of the knee joint 1.

An inferior lateral rigid elongated support member 39 is pivotallyconnected to the lateral terminal member 31 of the rigid posterior strut25 at a first pivot point by a pivot pin 41 and extends down along thelateral side of the leg 13. A superior medial rigid elongated supportmember 43 is pivotally connected to the terminal member 33 of theadjustable rigid posterior strut 25 at a second pivot point by pivot pin45, and extends upward medially along the thigh 7.

The support members 39 and 43 are secured to the leg 13 and thigh 7respectfully by anchoring devices 47 and 49. The anchoring devices 47and 49 each include a sleeve 51 of a non-slip cushioning material, suchas, for instance, neoprene, and a pair of straps 53 which are threadedthrough buckles 55 on the support members 39 and 43 and secured such asby VELCRO fasteners (not shown). These anchoring devices 47 and 49permanently secure the support members 39 and 43 to the fleshy portionsof the leg 13 and the thigh 7, respectively, so that forces aretransmitted through these support members into the large muscles of theextremity 3.

The brace 23 is also provided with a pair of stiff, semi-rigid, anteriorcuff members 57. These cuff members are generally triangular in shapewith one edge 59 secured to the associated elongated support member 39or 43 and with the opposing vertex 61 pivotally connected, such as witha snap fastener 63, to a connection point on the terminal member 31 or33 opposite to the terminal member to which the associated supportmember 39 or 43 is secured. The pivots formed by the fastener 63 arelaterally aligned with the corresponding pivot points of the elongatedmembers to which the cuffs are attached along the edge 59. The cuffmembers 57 are unsnapped and opened for applying the brace 23 to theextremity 3, and then are wrapped around and in front of the thigh andleg and snapped in place.

With the brace 23 in place, lateral blows to the leg 13 are partiallyabsorbed by the muscles in the leg 13 with the remainder transmittedthrough the adjustable rigid posterior strut 25 to the elongated medialsupport member 43 which pulls the thigh 7 laterally with the leg anddissipates the transmitted energy into the muscles of the thigh. Inresponse to a -lateral blow to the thigh 7, the force not absorbed bythe thigh muscles is transmitted by the elongated support 43, around theknee joint 1 by the rigid posterior strut 25 and through the elongatedsupport member 39 into the fleshy portion of the leg 13. The torsionforce generated by rotation of the thigh with the foot planted istransmitted around the knee joint 1 by the rigid posterior strut 25, andthrough the elongated member 39 into the leg 13. The stiff cuff members57 help to balance the rotational forces and to dissipate additionalenergy into the leg muscles. Anterior and posterior forces applied tothe leg 13 or the thigh 7 are similarly transmitted around the kneejoint 1 through the adjustable rigid posterior strut 25 with theassistance of the stiff cuff members 57.

Operation of the knee brace in accordance with the invention isillustrated by FIGS. 2 and 3. With the leg extended as shown in FIG. 2,the adjustable rigid posterior strut 25 extends substantiallyhorizontally, rearward into the popliteal area 29 behind the kneejoint 1. When the joint is flexed as shown in FIG. 3, the fleshyposterior portions of the leg (the calf) and thigh reposition theadjustable rigid posterior strut 25. This repositioning rotates theterminal portions 31 and 33 so that the pivot points at which theinferior and superior support members are attached are rotated toaccommodate for the femoral rollback which is illustrated in FIG. 3.Thus, the knee brace in accordance with the invention is automaticallyand correctly positioned by the natural movement of the extremity 3thereby eliminating the need for complex joint mechanisms which aresometimes ineffective because of slippage of the brace during flexionand extension.

FIG. 4 illustrates in detail the adjustable rigid posterior strut 25 ofthe invention. The arcuate member 27 has a longitudinal axis 65 and iscomposed of two halves 67 and 69, each of which is substantially a 90°sector of a circle. Confronting ends of the halves 67 and 69 havelongitudinal bores 71. An elongated piece in the form of a pin 73telescopes into the bores 71. Each of the halves 67 and 69 has a slit 75extending the length of the bore 71. Confronting radial flanges 77 alongeither side of the slits 75 are drawn together by screws 79 to formclamps which secure the ends of the pin 73 in the bores 71 in a fixedposition.

The free ends 81 and 83 of the halves 67 and 69, respectively, havelongitudinal bores 85. Slots 87 through the walls of the arcuate membersextend a substantial length along the bores 85. Confronting radialflanges 89 on either side of the slots 87 are drawn together byadditional screws 91 to form clamps for securing the mounting members 35and 37 to the arcuate member 27 as will be seen.

The mounting members 35 and 37 each have an elongated member in the formof a stem 93 which telescopes into the bore 85 in one of the halves 67and 69 of the arcuate member 27 and is secured in a fixed position bythe clamps formed by the flanges 89 and screws 91.

The terminal members 31 and 33 are secured to the mounting members 35and 37, respectively, by adjustable attachments on the mounting members,preferably in the form of ball and socket connectors 95. As shown inFIG. 5, these connectors 95 include balls 97 on the ends of the mountingmembers 35 and 37. Bosses 99 on the rear edges of the terminal members31 and 33 have rearwardly facing bores with spherical bottoms 101 whichdefine the sockets for the balls 97. Lock nuts 103 which thread onto theouter surface of the bosses 99 clamp an annular ring 105 with aspherical inner surface against the ball 97 to lock the terminal members31 and 33 in fixed positions relative to the mounting members 35 and 37.

As can be appreciated from FIG. 4, the adjustable rigid posterior strut25 of the invention offers great flexibility in the adjustment of thebrace 23. The adjustable connection between the two halves 67 and 69 ofthe arcuate member 27 of the posterior strut 25 allows adjustment of thelateral/medial distance between the terminal members 31 and 33 byloosening the screws 79, sliding the stem 73 in the bores 71, and thenfixing the two halves in this position by tightening the screws 79.Adjustment of the position of the terminal members 31 and 33 relative toeach other in the sagittal plane can be made by again loosening thescrews 79 and rotating the halves 67 and 69 about the stem 73 to adesired position and then retightening the screws 79. Preferably, thestem 73, and the bores 71 are fluted as at 107 to aid in fixing theangular position of the two halves 67 and 69.

The strut 25 may be adjusted in the anterior/posterior direction throughloosening of the screw 91 and sliding the stems 93 of the mountingmembers 35 and 37 inward or outward in the bores 85 in the ends 81 and83 of the arcuate halves 67 and 69, and then retightening the screws 91.By loosening the screws 91 and rotating the mounting members 35 and 37about the longitudinal axis 65 of the arcuate member 27 and thenretightening the screws 91, the terminal members 31 and 33 can berotated in the coronal plane to a desired fixed position relative to thearcuate member 27. Again, the stems 93 and bores 85 can be fluted as at109 to lock the mounting members 35 and 37 in fixed positions relativeto the arcuate members 27 with less torque required on the screws 91.

The ball and socket connectors 95 permit adjustment of the terminalmembers 31 and 33 in all three planes about the superior/inferior,medial/lateral and anterior/posterior axes relative to the mountingmembers 35 and 37.

FIG. 6 illustrates a mechanism for adjustment of the anterior cuffs 57which may be necessitated by adjustments, especially large adjustments,to the posterior strut 25. A pin 111 forms a fixed pivot for attachingthe cuff member 57 to the elongated support member 43. Fasteners in theform of screws 113 extend through arcuate slot 115, which are generallytransverse to the edge 59 of the cuff and spaced above and below thepivot pin 111. The screws 113, which are threaded into the elongatedsupport member 43, are loosened to adjust the angular position of thecuff member 57 to align the vertex 61 with the fastener 63 on terminalmember 31. The need for and the amount of this rotation is determined bythe adjustment, if any, made to the posterior strut 25. The screws 113are then tightened to clamp the cuff member 57 to the elongated supportmember 43 in the desired fixed angular position. A similar adjustmentmechanism is provided for the cuff 57 secured to the other elongatedsupport member 39.

For active (functional) use of the knee joint where maximum support isrequired, elongated support members pivoted to the strut 25 can beprovided along both sides of the thigh and leg as described in U.S.patent application Ser. No. 07/662,879 which has been incorporated byreference into this application. Thus, a lateral superior elongatedsupport member (not shown) may be pivoted to the terminal member 31, andsecured to the thigh by an anchoring device 47. Similarly, a medialinferior elongated support member (not shown) can be pivoted to terminalmember 33 and secured to the leg by an anchoring device 49. Additionalanterior cuff members (not shown), attached to these additionalelongated support members and criss-crossing in front of the thigh andleg can also be provided on the functional brace in accordance with theinvention.

As the adjustable rigid posterior strut 25 serves as the central elementto which the other elements of the brace 23 are connected, eitherdirectly or indirectly, the various adjustments made to the posteriorstrut 25 set the position of the other elements. The versatility of theadjustable knee brace in accordance with the invention allows an off theshelf brace to be used for patients with extremities of various sizesand shapes. Only a very few, perhaps two or three, sizes of brace needbe stocked, as those stocked parts can be assembled and adjusted tocover a full range of sizes. Furthermore, the versatility of theadjustable brace allows it to be customized for the invariabledeviations from the ideal knee joint and for a large range ofdeformities caused by disease or injury. Furthermore, the brace can beperiodically adjusted during use to accommodate for changes such as thegrowth of a child, or a reduction in swelling.

The following table indicates in general terms exemplary problems ordeformities, the conditions which typically give rise to this problem ordeformity and the major adjustment to the posterior strut which may beused to compensate for this condition. It will be obvious that in manyinstances, the major adjustment will give rise to the need foradditional adjustments at other connections to maintain the correctkinematics of the knee joint. For instance, if the two halves 67 and 69of the arcuate member 27 are rotated about the pin 73, it may benecessary to rotate the mounting members 35 and 37 about the stemportions 93 and to adjust the ball and socket connections to maintainthe terminal members 31 and 35 generally perpendicular to the axis ofrotation of the knee joint.

                  TABLE 1                                                         ______________________________________                                        COMMON KNEE PROBLEMS AND RELATED                                              CORRECTIONS USING POSTERIOR STRUT BRACE                                       PROBLEM                                                                       OR        COMMON ASSOCIATED CORRECTION                                        DEFORMITY CONDITIONS        OF PROBLEM                                        ______________________________________                                        Varus     Osteoarthritis,   Tilt Posterior                                    Deformity Developmental     Strut in Coronal                                  (bowed-kneed)               Plane (medial                                                                 high) - rotate                                                                67-69 about 73                                    Valgus    Rheumatoid Arthritis,                                                                           Tilt Posterior                                    Deformity Osteoarthritis, Post-                                                                           Strut in Coronal                                  (knock-kneed)                                                                           Traumatic         Plane (lateral                                                                high) - rotate 67                                                             and 69 about 73                                   Internal  Developmental or  Adjust Strut in                                   Rotation  Posti-traumatic   Horizontal Plane                                  Deformity Posteriolateral   Slide 93 in 85                                    (pigeon-toed)                                                                           Ligamentous Laxity                                                                              (Elongated                                                                    Laterally)                                        External  Developmental or  Adjust Strut in                                   Rotation  Post-traumatic    Horizontal Plane                                  Deformity Posteromemdial    (extend on one                                    (ballet dancer)                                                                         Ligamentous Laxity                                                                              side) - Slide 93                                                              in 85 (Elongated                                                              Medially)                                         Flexion   Osteoarthritis    Adjust Strut                                      Contracture                                                                             Post-operative,   about Axis of                                     (can't straighten                                                                       Rheumatoid Arthritis,                                                                           Rotation. Rotate                                  leg)      Post-traumatic    31 or 33 relative                                                             to 27                                             Extension Developmental or  Adjust Strut                                      Deformity Post-traumatic    about Axis of                                               Ligamentous Laxity                                                                              Rotation. Rotate                                                              31 or 33 relative                                                             to 27                                             Growing Child                                                                           Normal Develop-   Expand Strut.                                               ment of joints    slide 67 and 69                                                               on 73. Slide 93                                                               out of 85                                         Right/Left                                                                              Various           Individually                                      Differences                 adjust L/R                                                                    as required.                                      Swollen Knee                                                                            Post-traumatic or Expand Strut                                                Post-operative    Slide 67 and 69                                             Phlebitis         on 73                                             Atrophied Knee                                                                          Post-injury       Contract Strut                                              Atrophy           Slide 67 and 69                                                               on 73                                             ______________________________________                                    

It can be seen from the above that the invention provides greatversatility to offset the axis of rotation of the brace, as well asindividually adjust the lateral to medial distance and offset thevertical axis of action of the affected hinge point to compensate forindividual knee characteristics, or to provide thesurgeon/physiotherapist a means for adjusting for abnormal knees; foreither improved brace fit; optimizing the brace function/action forindividual patients; or compensating for, or controlling specificmotions or actions.

While specific embodiments of the invention have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangements disclosed are meant to be illustrative only andnot limiting as to the scope of the invention which is to be given thefull breadth of the appended claims and any and all equivalents thereof.

What is claimed is:
 1. An adjustable rigid posterior strut for a kneebrace having elongated leg attachment members, said strut comprising:arigid arcuate member having first and second ends and a longitudinalaxis; first and second terminal members having pivot connections adaptedfor attachment to the elongated attachment member; and first and secondmounting means rigidly fixing said first and second terminal members tosaid first and second ends respectively of said arcuate member inselected positions relative to said arcuate member.
 2. The strut ofclaim 1 wherein said first and second mounting means comprise meansadjustably fixing said first and second terminal members at selectedfixed rotational positions about said longitudinal axis.
 3. The strut ofclaim 1 wherein said first and second mounting means comprise meansadjustably fixing said first and second terminal members at selectedfixed axial positions along said longitudinal axis.
 4. The strut ofclaim 1 wherein said first and second mounting means include meansadjustably fixing said terminal members in selected fixed rotationalpositions about a lateral axis transverse to said longitudinal axis. 5.The strut of claim 1 wherein said first and second mounting meansinclude means adjustably fixing said terminal members in selected fixedrotational positions about a vertical axis transverse to saidlongitudinal axis.
 6. The strut of claim 1 wherein said first and secondmounting means include mounting members having elongated membersextendable axially with respect to said first and second ends of saidarcuate member and rotatable about said longitudinal axis of saidarcuate member, and first and second securing means fixedly securingsaid elongated members in selectable axial and rotational positionsrelative to said first and second ends respectively of said arcuatemember.
 7. The strut of claim 6 wherein said first and second elongatedmembers telescope with said first and second ends respectively of saidarcuate member, and said first and second securing means comprise clampsclamping said elongated members in selectable fixed axial and rotationalpositions relative to said first and second ends of said arcuate member.8. The strut of claim 7 wherein said elongated members and said ends ofsaid arcuate members are fluted.
 9. The strut of claim 7 wherein saidends of said arcuate member have longitudinal bores in which saidelongated members telescope, and wherein said ends have longitudinalslits extending along said bores and wherein said clamps compriseconfronting flanges extending radially outward adjacent said slits andscrew members drawing said flanges together to clamp said elongatedmembers in said bores.
 10. The strut of claim 9 wherein said elongatedmembers and said bores are fluted.
 11. The strut of claim 6 wherein saidfirst and second mounting means further include first and secondadjustable attachment means fixing said first and second terminalmembers in selectable positions to said first and second mountingmembers.
 12. The strut of claim 11 wherein said first and secondadjustable attachment means comprise ball and socket connections betweensaid first and second terminal members respectively and one of saidmounting members, and tightening means fixing said ball and socketconnections with said first and second terminal members in selectedpositions relative to the mounting members.
 13. The strut of claim 11wherein arcuate member comprises first and second halves rotatable aboutsaid longitudinal axis to selectable angular positions with respect toone another, and connecting means fixedly connecting said first andsecond halves together at a selected angular position.
 14. The strut ofclaim 6 wherein said arcuate member comprises first and second halvesrotatable about said longitudinal axis to relative angular positionswith respect to one another, and connecting means fixedly connectingsaid first and second halves together at a selected angular position.15. The strut of claim 14 wherein said first and second halves areextendable axially along said longitudinal axis to selected axialpositions relative to one another, and wherein said connecting meansincludes means fixedly connecting said first and second halves togetherat a selected axial position.
 16. The strut of claim 15 wherein saidconnecting means includes an elongated piece which telescopes with andis rotatable about said longitudinal axis with respect to said first andsecond halves, and means clamping said elongated piece to said first andsecond halves with said first and second halves in said selected axialand angular positions with respect to one another.
 17. The strut ofclaim 16 wherein said first and second halves have confrontinglongitudinal bores with longitudinal slits extending along said bores,wherein said elongated piece is a pin which telescopes and rotates insaid bores, and wherein said clamping means comprises confrontingradially, outwardly extending flanges along each side of said slits andscrew members drawing said flanges together.
 18. The strut of claim 6wherein said arcuate member comprises first and second halves extendableaxially along said longitudinal axis to selected axial positionsrelative to one another, and connecting means fixedly connecting saidfirst and second halves together at a fixed axial position.
 19. A bracefor a knee joint joining thigh and leg limb members, said bracecomprising:a rigid posterior strut comprising a rigid arcuate memberadapted to extend through a popliteal space behind the knee joint andhaving first and second ends and a longitudinal axis, first and secondterminal members and first and second mounting means adjustably fixingsaid first and second terminal members to said first and second endsrespectively of said arcuate member in selected axial and angularpositions; a first support member pivotally connected to said firstterminal member and adapted to extend upward along a first side of thethigh; a second support member pivotally connected to said secondterminal member and adapted to extend downward along a second side ofthe leg opposite the first side of the thigh; first support meansadapted to secure said first support member to the thigh; and secondsupport means adapted to secure said second support member to the leg.20. The brace of claim 19 including first and second generallytriangular cuff members having a support edge and a vertex opposite saidsupport edge, first attaching means firmly attaching the support edge ofthe first cuff member to the first support member with said first cuffmember bowed anterior to the thigh and the vertex of the first cuffmember pivotally attached to the second terminal member, and secondattaching means firmly attaching the support edge of the second cuffmember to the second support member with said second cuff member bowedanterior to the leg and the vertex of the second cuff member pivotallyattached to the first terminal member.
 21. The brace of claim 20 whereinsaid first and second attaching means comprise means firmly fixing thesupport edges of said first and second cuff members in selected axes ofat least two positions relative to said first and second elongatedmembers, respectively.
 22. The brace of claim 20 wherein said first andsecond attaching means each comprise a pivot member pivotally securing apivot point along the support edge of the first and second cuff membersrespectively to the support member, and fastening means spaced from saidpivot member accommodating rotation of said cuff member about the pivotpoint to a selected angular position, and fixedly securing said supportedge to said support member at said selected angular position.
 23. Thebrace of claim 22 wherein said fastening means comprise a slot in saidcuff member and a fastener extending through said slot and clamping saidcuff member to said support member.
 24. The brace of claim 22 whereinsaid fastening means comprise slots in said cuff member spaced inopposite directions along said support edge from said pivot member, andfasteners extending through each slot and clamping said cuff member tosaid support member.
 25. The brace of claim 19 wherein said arcuatemember has first and second halves rotatable about said longitudinalaxis to a selected angular position with respect to one another, andextendable axially along the longitudinal axis to a selectable axialposition with respect to one another, and connecting means fixedlyconnecting said first and second halves together at a selected angularand selected axial position.
 26. The brace of claim 25 including firstand second generally triangular cuff members having a support edge and avertex opposite said support edge, first attaching means firmlyattaching the support edge of the first cuff member to the first supportmember with said first cuff member bowed anterior to the thigh and thevertex of the first cuff member pivotally attached to the secondterminal member, and second attaching means firmly attaching the supportedge of the second cuff member to the second support member with saidsecond cuff member bowed anterior to the leg and the vertex of thesecond cuff member pivotally attached to the first terminal member. 27.The brace of claim 26 wherein said first and second attaching means eachcomprise a pivot member pivotally securing a pivot point along thesupport edge of the first and second cuff members respectively to thesupport member, and fastening means spaced from said pivot memberaccommodating rotation of said cuff member about the pivot axis to aselected angular position, and fixedly securing said support edge tosaid support member at said selected angular position.